The purpose of this study is to examine the effectiveness of vitamin D3 versus vitamin D2 in raising vitamin D levels and suppressing parathyroid hormone levels in patients with kidney disease who are not on dialysis.

Subjects will be randomized and assigned to one of the treatment groups (D2 or D3). Subjects will be dispensed a supply of 1.25 mg cholecalciferol/ergocalciferol tablets, depending on their randomization outcome. The number of pills dispensed and medication instructions will be determined by their 25OHD level and K/DOQI guidelines. Both Study personnel and subject will be blinded to randomization group.

The treatment phase will be 24 weeks in duration with lab visits every 6 weeks. All laboratory specimens will be drawn either at CCF Main hospital labs or at a CCF family Health center lab. Subjects will be have telephone interviews at week 4, 10, 16, 22 and possibly at weeks 28 and 34.

Inclusion Criteria:

• Adults ≥ 18 years
• Chronic kidney disease stage 3-4 (eGFR 15-59 mL/min/1.73m2 body surface area, calculated using the MDRD Study equation GFR calculator)
• Hypovitaminosis D (serum 25OHD < 31 ng/mL)
• Secondary hyperparathyroidism (Intact PTH > 70 pg/mL for stage 3, and iPTH > 110 pg/mL for stage 4)

Exclusion Criteria:

• Initiation of vitamin D therapy between the time of the lab draw used for screening and the screening process
• History of liver failure
• History of intestinal malabsorption or chronic diarrhea
• Serum calcium level greater than 10.2 mg/dL
• Treatment with an activated vitamin D formulation (calcitriol, doxercalciferol or paricalcitol) within the past 6 months
• Treatment with phenobarbital, phenytoin, rifampicin, sucralfate, steroids, digoxin, or other medications that could affect vitamin D metabolism
• Primary hyperparathyroidism, active of a prior history of such
• Active malignancy excluding basal cell or localized squamous cell skin cancer
• Subject is pregnant (e.g. positive HCG test) or breast-feeding
• Refusal to use highly effective contraceptive measures (as determined by the investigator) throughout the treatment phase of the study
• Serum phosphorus level greater than 4.5 or treatment with an oral phosphate binder within the past 6 months
• Treatment with cinacalcet or other calcimimetic within the past 6 months
• Anticipated dialysis within 6 months after randomization
• Inability to swallow tablets
• Known sensitivity, intolerance, or other adverse response to the study drugs which would prevent compliance with study medication
• Have an unstable medical condition, defined as having been hospitalized within 30 days before screening, the expectation of recurrent hospital admissions or life expectancy of less than 6 months in the judgment of the investigator
• Subject is currently enrolled in, or fewer than 30 days have passed since subject has completed another investigational device or drug study(s); or subject is receiving another investigational agent(s).
• Current treatment with vitamin D 50,000 IU

Adverse Events were not logged by study arms.

Early termination of the study lead to small numbers of subjects analyzed.